The use of twist-on electrical wire connectors in areas that may be wet or exposed to moisture requires the bared ends of the electrical wires, which are mechanically joined through a twisting action, to be protected from exposure to moisture, not only immediately after formation of the electrical connection but in some cases for years or decades after formation of the electrical connection. Compounding the problem of waterproofing an electrical wire connection and in particularly a twist-on wire connector where the electrical wire connection may have to last for decades are the conditions existing during the formation of the electrical connection. Typically, an electrical wire connection is formed on-the-go and in the field where the field conditions and the environment may be adverse to formation of an electrical wire connection and the skills of the electricians forming the electrical wire connections may range from novice to expert.
In one type of waterproofing an electrical wire connection an electrician forms an electrical connection in a sealant filled twist-on wire connector by twisting the wires in relation to the housing of the twist-on wire connector. In the sealant filled wire connectors a sealant, which is located in a central cavity of the twist-on wire connector, provides a waterproof covering over the electrical junction between a set of bared wire ends. Examples of sealant filled electrical twist-on wire connectors are shown in U.S. Pat. Nos. 5,113,037; 5,023,402 and 5,151,239. In these type of sealant filled twist-on wire connectors the wires are inserted through a pierceable cover and into a viscous sealant contained in a wire cavity of the twist-on wire connector. The housing is then twisted with respect to the wires to bring the bared ends of the wires into electrical contact with each other in the presence of the sealant, which forms a sealant air interface to shield the electrical connection from the environment. In some embodiments sleeves are placed on the twist-on wire connector to contain extra sealant. In other embodiment the twist-on wire connector includes clips for looping the wires thereon to prevent the wires from pulling out of the twist-on wire connector.
Another example of a sealant filled wire connector is shown in King U.S. Pat. No. 8,431,824. King U.S. Pat. No. 8,431,824 discloses a direct bury splice kit having a sealant filled twist-on wire connector formed as an integral part of an elongated tube, which contains a sealant. In this example the formation of a sealant covered wire connection occurs within the tube and in one continuous action.
In the above examples the formation of an electrical junction in a sealant filled twist-on wire connector the water resistant wire connection is made in the field and on-the-go by inserting a plurality of bared ends of electrical wires into the waterproof sealant and twisting the wires with respect to the housing of the twist-on wire connector to form a sealant covering around the plurality of bare ends of electrical wires, which are in electrical contact with each other, and a spiral housing located within the twist-on wire connector. This type of sealant filled twist-on wire connector is popular since the formation of the electrical wire connection and the formation of the sealant covering over the bared ends of the electrical wires can be quickly formed without the aid of special tools.
In an immersion method of waterproofing the electrical connection is formed in an electrical wire connector, which contains no sealant. Once the electrical connection is formed the entire wire connector with the electrically connected wire ends therein is immersed in a waterproof sealant. An example of an immersion type of waterproofing an electrical wire connection using a twist-on wire connector can be found in the commercially available direct bury splice kit sold by the 3M electrical products of Austin Tex. and Fox U.S. Pat. No. 4,839,473. Typically, the kit includes, a twist-on wire connector, an elongated tube with an integral cover that is closeable on the wires to provide stain relief and a waterproof sealant, which is located in one end of the elongated tube. The twist-on wire connector and the tube are both stored loosely in a plastic package that is breached before the twist-on wire connector and the elongated tube can be used. The elongated tube contains a sealant in a closed end of the tube and a cover proximate an open end of the tube. The cover can be closed which typically clamps the wires extending into the tube to support the wires with respect to the elongated tube and thus reduce stress on the electrical connection in the twist-on wire connector. In this type of electrical connection formation the twist-on wire connector contains no sealant but once the electrical connection is formed in the twist-on wire connector the entire twist-on wire connector with the electrical connection therein is immersed in the sealant. This type of waterproofing is referred to as an immersion type since the entire twist-on wire connector is immersed in the sealant to form a sealant air interface to shield the wire connector as well as the electrical connection from the environment.
The immersion method of waterproofing twist-on wire connectors, which is shown in U.S. Pat. No. 8,431,824, discloses a direct bury splice kit including an elongated housing having a chamber for inserting a wire connector therein and a lateral wire cradle together with a cover having at least one jaw to clamp a portion of a wire against the wire cradle. Clamping the wire to the container inhibits or prevents loosing of the electrical wire connection while maintaining the electrical wire connection between the ends of wires in a waterproof condition in the sealant of the elongated housing. This type of waterproofing a twist-on electrical wire connector relies on immersion of the twist-on wire connector with the formed electrical junction therein into a body of sealant within a tube or the like.
In contrast U.S. Pat. No. 7,170,005 shows an example of another the twist-on wire connector containing a sealant where the twist-on wire connector is an integral part of a one-piece tube, which eliminates the handling of a separate wire connector. The tube also includes a dome for extending into the tube to force the wires against the tube sidewalls. In this example the formation of the wire connection occurs in the presence of the sealant within the twist-on wire connector, which is a part of a tubular housing.
The above described methods of forming a water resistant electrical connection utilizing twist-on wire connectors fall into two main methods of waterproofing i.e. either waterproofing while forming an electrical connection in a sealant filled twist-on wire connector or waterproofing after forming an electrical connection by immersing the entire wire connector in a sealant. Either method of waterproofing the electrical junction has been found to work well, however, failures have been known to occur with either method of waterproofing.
While such failures are rare the time to failure varies since the failure of electrical connections have been known to occur many months or even decades after the formation of the electrical connection. While it difficult to determine the actual cause of the electrical failure there has been speculation that the failure of the electrical connection, which in some cases is due to exposure of a portion of the bared end of the electrical wires, may be due to human error in forming the electrical connection or human error in the immersion of the twist on wire connector in a body of sealant. While the failure of twist-on wire connectors occurs in both the sealant filled wire connector and the sealant immersed wire connector the time of failure and location of the failure makes is difficult to diagnose the events that lead to the failure of the electrical connection.
Consequently, conditions exist where waterproof twist-on wire connectors, which have a viscous sealant for encapsulating the bared ends of an electrical wire, fail causing a short. Likewise there exist conditions where the twist-on wire connectors, which are immersed in a sealant, also fail. In either case the failures are extremely rare, however, the shear number of twist-on electrical wire connectors used at a work site and through the electrical industry increases the odds that an electrical connection may fail at a job site with the potential for disastrous results.